<!DOCTYPE html>
<html>
<head>
	<meta charset="utf-8">
	<title>点击随机产生背景色</title>
	
</head>
<body>
	<button onclick="beijingColor()">随机产生背景色</button>
	
	<script type="text/javascript">
		function beijingColor()
		{
			var bg = document.getElementsByTagName("body")[0];
			var r = Math.round(Math.random() * 255);
			var g = Math.round(Math.random() * 255);
			var b = Math.round(Math.random() * 255);
			var co = "rgb(" + r + "," + g + "," + b  + ")";
			bg.style.background = co;
		}
	</script>
</body>
</html>